


Underground

by midnightsong22



Category: Voltron: Legendary Defender
Genre: Canon Compliant, Established Relationship, M/M, Post Season 7, Romance, but not season 8 canon compliant
Language: English
Status: Completed
Published: 2018-12-24
Updated: 2018-12-24
Packaged: 2019-09-26 12:18:34
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,445
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17141621
Author URL: https://archiveofourown.org/users/midnightsong22/pseuds/midnightsong22
Summary: A routine mission ends in disaster when the Black Lion disappears from the battlefield. Shiro isn't afraid to do whatever it takes to get Keith back, but Keith must solve the mysteries surrounding his own disappearance if he wants to make it back to his friends in one piece. Sheith Secret Santa for bakuraes@twitter. I hope you enjoy it!





	Underground

**Author's Note:**

> This ended up way longer than I was expecting but I hope that turns out to be a good thing.

It must be some cruel twist of fate, Shiro thought bitterly, clutching Keith’s bright red uniform to his chest. After literal _years_ of Keith desperately looking for and saving him over and over again, it stood to reason that one day Shiro would have to do the same for him.

Yet he still could not believe it was happening.

Shiro let out a shaky breath, letting Keith’s uniform jacket fall into his lap as he raked his left hand through the white locks at his forehead. He had been sitting on his- _their_ -bed in the darkness for just over an hour, and it had been about twelve hours since Keith’s disappearance.

The worst part was that everything had been so normal. Atlas had picked up on a planet’s distress signal, warped to its location, and Voltron had been deployed to take out the Galran sentries and set the local population free. It had been such a routine mission in fact, that Atlas did not even have to breach the atmosphere to assist. Voltron was more than sufficient to get the job done.

Yet the planet itself proved harsher than they expected. After freeing the major city of Galran control, the paladins had been instructed to go several miles south to the only other Galran outpost on the planet. It had supposedly been constructed to harvest the planet’s source of quintessence and, if left the way it was, would eventually kill the planet and every living creature on it.

The locals--a species called Dregmos--had warned the paladins to take care on their way there, but none of them had anticipated the mysterious, thick fog that had rolled in as they flew. It had enveloped their lions completely with visibility at zero as it somehow interfered with their communicators and displays. The only thing that kept them in formation and moving forward was Pidge’s upgraded scanners that allowed them to track each other’s positions.

But as quickly as the fog had rolled in, it disappeared… and so did the Black Lion.

It was unfortunate how things developed after that. The fog had dissipated just as the paladins reached the outpost, and they were greeted with heavy gunfire and enemy ships. Without the Black Lion they could not form Voltron but they were too deep within enemy territory to try to pull back and look for Keith.

It took nearly half an hour for the four paladins with Atlas’ assistance to take down the base and all of its sentries, but they couldn’t celebrate their victory when there was still no sign of the Black Lion or her paladin.

Pidge had done her best to retrace the Lions’ path across the terrain, but making progress proved difficult as the fog would reappear and continued to mess with their equipment. Further investigation with the Dregmos only confirmed what they had feared: that the fog was responsible for many missing pilots and adventurers, never to be seen again.

“Isn’t there _anything_ you know about what causes the fog or what it does to people?” Pidge had asked, pounding her fist down upon the top of a scanner she was working on.

Even after returning from the fog to the city, the machinery refused to turn back on.

A group of Dregmos had stood solemnly before them, exchanging looks. One stepped forward, a tall reptilian-like creature with blue scales and an ornate white robe with gold embellishments draped around its shoulders.

“We are sorry paladins...” the blue Dregmos began, clawed hands fidgeting in front of themself, “But the fog comes and goes randomly. We have been unable to study it due to its effect on our technology. This planet used to flourish with life, but that changed when the Galra arrived thousands of years ago. They brought _something_ with them that lives beneath the surface and destroys the land above. The fog is just one of its many negative effects. This city is the largest habitable stronghold on the planet, yet I fear that soon this land too will fall.”

It could never be easy, huh?

Shiro let his head fall back against the wall, thinking over everything they’d learned. The other paladins had convinced him to go to bed for the night, but the only reason he conceded was so that they would not worry. He didn’t actually expect to sleep tonight. How could he after getting used to sleeping with a warm body pressed against his own?

Had it really only been two weeks since the Atlas left Earth to continue its mission to end the war and restore peace? Had it really only been two weeks since Shiro climbed to the top of the Black Lion to sit with Keith, only for it to culminate with them finally confessing their feelings for one another? He can still feel the ghost of Keith’s lips against his own, the promise from his best friend (and now his lover) that they will always be together.

Only for the universe to rip them apart once again.

A flash of light in the corner of the room was the only warning he got before Keith’s wolf was on the bed with him, whining and pressing its face into Shiro’s chest.

“I know buddy,” Shiro replied, stroking the wolf’s dark fur until it settled down beside him, resting its head on Shiro’s lap.

Even the wolf couldn’t locate Keith’s position, making this the longest it had ever gone without Keith’s presence since they’d met two years ago.

“I’m sorry. I’ll find him and bring him back,” Shiro promised.

 

“Pidge, Hunk, Allura, Lance! Anyone! Come in!” Keith yelled over the comms, but there was no response except static.

Ever since the strange fog moved in, Black’s sensors and displays had gone offline, plunging the cockpit into darkness. The only light left came from an upgraded scanner which at least showed him the others’ positions fanned out on either side of him. Keith kept his grip tight on the controls and focused on staying on course.

“Can anyone hear me? Pidge, can you get anything else online or-”

A rumble in his mind from Black was the only warning he got before he felt the impact as she crashed into something directly in front of them. He was jerked forward in his seat, his hands slipping off the controls. In the darkness it took a few moments to reorient himself, grappling for the controls as Black plumented downward. His hands wrapped around them again, and he pulled Black out of her descent.

He let out a shaky breath and his eyes flickered over to the scanner. The others had gone on ahead but they were still within range. It took only a few moments for him to push Black back up to speed and into formation.

“Alright, let’s pull back up.”

This time, however, not even Black was prepared for the impact from above, and with that her engines also went offline, and Keith found himself dropping even further down into the darkness below.

 

Keith groaned, his whole body aching from the multiple impacts. He thinks he must have blacked out at some point because he couldn't remember landing… or, he supposes, crashing.

The Black Lion, after losing power completely, must have landed on her side, because Keith could feel the entire cockpit leaning left. The darkened screens made it impossible for him to assess the damage of the Lion herself. He felt around his seat, releasing the restraints that held him in place and felt himself fall slightly, catching onto the control panel in front of him to keep from falling out of his seat completely.

He felt along various dials and buttons, trying his best to get anything working. He toggled both the lights and radio but got nothing but darkness and silence.

Keith sighed, pushing himself off of his seat and quickly making his way to the port door that led outside. It’d been awhile since he’d had to open it manually, and it took him a few moments to get it to crack open. As he started to push through, he was surprised to see light coming from the other side.

Finally, he made his way out and he stared in wide eyed wonder at the the desert spread out around him.

“Impossible,” he whispered, as he looked up to see blue skies overhead.

He couldn’t have possibly fallen as far as he had and still be able to see the sky. Not to mention, the planet they had been helping had rocky cliffs and barren land, but not sandy deserts.

Keith allowed himself to drop to the ground beside the Black Lion and he kicked at the sand. It looked real enough as it clouded up around his foot. Maybe he had somehow been warped to another planet?

“Paladins!” he tried, hoping his helmet might still function, “Atlas! Can anyone hear me?”

He surveyed the land around him, eyes landing on a particularly tall dune about half a mile away. Maybe he could get a signal if he was just a bit higher.

“I’ll be right back,” he promised, patting his hand gently on the Lion’s face.

Using his jetpack he propelled himself forward, trying to cross the distance quickly. All the while he tried talking into his helmet, on the off chance that anyone might be listening.

“Shiro? Are you there?” He said, trying not to let the panic set in, “I don’t know what happened but the Black Lion is unresponsive. We hit something and crashed hard. I can’t even tell if we’re on the same planet anymore. Can you hear me?”

By the time he made it to the top of the dune he was unsurprised to find that it made no difference. He still couldn’t get through to anyone.

He was cut off and completely alone.

Keith let himself sink to the ground, trying to keep himself calm and centered. Black may be unresponsive now, but with a little time she could come back online. Until then he just needed to try and figure out where he was and survive.

Without meaning to he found his thoughts, as always, drifting to Shiro. He couldn't help but compare the desert around him to the one on Earth, where he and Shiro used to hoverbike across the sand. Shiro’s laugh had been so carefree back then, and he always tried his best to draw that laugh out whenever he could.

Keith closed his eyes and couldn’t help but smile as he remembered how just the other night they had fallen into bed together. After a long day of traveling and stressing over the war, Keith had wanted to press Shiro down into the sheets and make him forget everything but his own name. But when Keith’s fingers had danced lightly against Shiro’s sides, Shiro had choked on a laugh that made Keith pause.

Shiro’s eyes widened and he had caught Keith’s hands in his own.

“Don’t you dare.”

Keith grinned, still straddling Shiro’s hips and leaned closer, “Whatever do you mean, _Captain_?”

Shiro’s eyes had narrowed and the ensuing tickle fight had left them both breathless with laughter. Shiro’s sides had always been sensitive and Keith took full advantage of his position pinning Shiro down, until Shiro managed to flip them, attacking Keith’s armpits and stomach.

By the time they ran out of steam and laughter, they were both on their sides facing one another, and Keith had made sure to kiss Shiro senseless.

“I love you Keith,” Shiro had whispered against his lips.

Keith opened his eyes to look out again over the desert in front of him, surprised to find that the sun was beginning to set.

“I love you too, Shiro,” Keith whispered to the horizon.

 

Shiro watched as Pidge pointed out the strange rock formation on the map that the Lions must have passed over the previous day. She explained how they had figured out from the backlogs of the scanners that Keith had momentarily been stopped, perhaps from crashing into something, before catching up. This location, she’d said pointing to the map, was about where it must have happened.

“The Dregmos said that this area has many canyons and openings that lead to an underground cave system. It used to be used for mining resources until the Galra arrived and it became too dangerous to go inside-”

“What, but why?” Lance cut in, “What did the Galra _do_ exactly?”

Pidge paused, eyes flicking to the side as if she were trying to find the words that wouldn’t send everyone into a panic. It made Shiro’s blood run cold.

“It’s some kind of creature...” She trailed off and took a deep breath, “The Dregmos don’t know much about it, except that it feeds off of the planet’s lifeforce, which is why it has become so barren. It started as some kind of Galran experiment, and anyone who tried to rise up against the Galra would be thrown down there with it.”

“And you think Keith might have ended up down there?” Shiro asked, trying to keep the panic out of his voice.

“But I mean he’ll be okay, right?” Hunk asked, always the optimist, “Keith is the strongest guy we know! There’s no way he’d let some monster get him. All he’ll need to do is find his way out and he’ll fly right back to us.”

“Normally I’d agree,” Pidge said, “But this _thing_ has the ability to make our tech go absolutely crazy on the surface. Just imagine what it could do to our Lions when we’re closer and… there’s something else.”

“What is it?” Shiro asked, hand clenching at his side.

“Apparently it also has the ability to thrall people… meaning that it draws people in deeper to devour them.”

The dawning looks of horror on everyone’s faces matched the ice cold fear that took grip of Shiro’s heart.

 

Keith didn’t mean to fall asleep, but he awoke to the night sky above him with the stars and moon shining brightly.

For a moment he thought maybe the Atlas had never left Earth, and they must still be preparing to leave. Maybe the planet he’d crash landed on had all been some crazy dream. But then he moved to sit up and felt the pain in his limbs from where he had been jerked around in his seat, and when he looked behind him he could still see the Black Lion on her side in the sand.

He looked back up to the sky, still wondering how he could even _see_ the sky right now with how far underground he must be. Until it finally occurred to him… he recognized these constellations.

He stood, quickly scanning the night sky. There could be no mistake, these were _Earth’s_ constellations. The very same that his father had taught him as a child, and the ones that he and Shiro had sat beneath together before Shiro had left for Kerberos.

“I’m on Earth,” He whispered in awe, “But how is that possible?”

He looked back down and he couldn’t believe he’d missed it. There, in the distance, he could see a wooden structure: the shack.

As if in a trance he found himself sliding down the dune and jetpacking towards it. Before he knew it he was standing on the porch and pushing the door open. He hadn’t had the chance to visit it before they’d left in the Atlas again. He hadn’t even been sure it had survived after the Galra takeover, but here it was. A bit dusty but still intact.

He was drawn in deeper into his old home. He’d spent a year living here, searching for a reason to go on after Shiro’s death. He stood in front of the wall with pins and strings, looking over the notes and pictures he’d taken. His fingers brushed over one note he’d written:

_It’s killing me when you’re away._

And then over a picture of him and Shiro the day of the launch. Keith had been so excited to see the ship up close. The ship that would take Shiro across the stars to become the first pilot to reach Kerberos. Even now it made his heart ache to think about. They never could have imagined what would happen back then.

The sound of footsteps from outside the shack had him immediately on guard, his bayard already called forth into his hand. He moved silently to the other side of the room and peeked out the window. He couldn’t see anything from his vantage point and just as he was about to slam open the door, there was a knock.

Still suspicious, he waited until there was another knock, a bit louder. He opened the door quickly, hoping to catch the person off guard and he pushed out his bayard to make whoever it was back up.

“Woah!” he heard the person say, and immediately Keith felt himself relax.

“Shiro, you found me,” Keith smiled.

 

Shiro sat with him on the shack’s poor excuse of a couch. Keith quickly recounted what had happened: the Black lion crashing, their descent underground, and their appearance here on Earth.

“It’s incredible, isn’t it?” Shiro replied, “We must have been teleported back here somehow.”

“Yeah I guess so, but I wonder why,” Keith hummed, considering everything, “How did _you_ get here Shiro? And where are the others?”

“The Lions weren’t functioning properly, so we set down next to the cave entrances and ended up looking for you on foot. Unfortunately, we were separated when I fell down one of the tunnels. I’m just glad those tunnels spat me out here with you.”

“Okay, then I guess we need to go find the others,” Keith stood, but Shiro grabbed his hand.

“Hey it’s okay,” Shiro replied, voice smooth as silk, “I told them that I’d find you. They’re probably back with their lions by now. Why don’t we take some time for ourselves.”

Keith felt the hairs on the back of his neck stand up, telling him that something was wrong. Something sounded off… yet his body suddenly felt lethargic, and Shiro pulled him back down onto the couch beside him.

He couldn’t quite shake the feeling that something was wrong, but Shiro was smiling again. That really sweet smile that made Keith’s heart soar. Shiro was laughing and it sounded like music. His jet black hair was exactly how Keith remembered it and he looked so young and carefree. Shiro’s hands grabbed his own, and for some reason Keith was caught off guard by the flesh of Shiro’s right hand. Didn’t there used to be a scar on Shiro’s face? Keith couldn’t remember.

There was a part of him screaming at himself that something was wrong. The Shiro he loved had white hair now and an Altean prosthetic to replace the arm he’d lost. The Shiro he knew had seen the horrors of the world but overcome them.

“Keith,” The Shiro in front of him murmured, “I love you.”

Keith gasped, unprepared for the sharp pain in his right leg. It felt as if it were burning. His head snapped down to look, but nothing was there. He looked back up to Shiro, and was caught off guard by his expression.

“No…” Shiro whispered, horror etched into his expression, “I don’t want to do this again… I won’t be another copy that’s used to hurt you.”

“Shiro what-”

“You need to run! Now!” Shiro cut him off, pushing him off of the couch and onto the floor, “Get back to your Lion!”

Before he could reply, both Shiro and the shack disappeared and he was suddenly very aware of his surroundings.

The cave was covered in bioluminescent plant life, allowing him to see the enormity of the cavern around him, the ceiling hundreds of feet above. His right leg was being constricted by one of many snake-like vines, that were pulling him deeper inside. He grabbed his bayard and struck at the vines, releasing their hold on him and he stood quickly, ready to run back to his lion.

However, he was distracted and horrified by what he saw in front of him. A giant flower bulb, nearly the size of Voltron, with thousands of vines connected to it and spreading out around it. Keith quickly scanned the room, and saw that almost all the plant life was connected to this central bulb. He also couldn’t ignore the scattering of bones at its base.

_This_ was what was killing the planet.

The vines around him were creeping slowly closer, and he stepped backwards, trying to avoid touching any of the plants directly. It couldn’t possibly see, so maybe he could avoid them altogether if he can just…

He looked up just in time to see one particular flower release spores into the air. He tried to turn away but had to take a quick breath. For a moment he was back at the shack, Shiro standing before him once again, a pained expression on his face. Keith closed his eyes and shook his head. When he reopened them the cavern was back.

So that was how he’d been misled. The spores were hallucinogenic. His helmet should have blocked them but-

He raised a hand to his face, feeling along the helmet, until he felt the crack in the glass. It must have been broken when he’d been jerked around during the crash, and he’d been breathing in those spores the entire time.

He needed to get out of here. Immediately.

Unlike the desert scene, it was a lot harder to see the Black Lion’s position in the cavern. With the last of its power, he used his jetpack to propel himself high enough to spot it, and when he set back down he took off running.

The entire cave seemed to be moving around him. He jumped over vines and kept a hand to the crack on his helmet, trying to keep the spores from getting in. He kept seeing glimpses of the desert, but he could still see the Black Lion. When he finally reached her, he had to cut away vines that had started to envelop her and he pushed his way back inside.

“C’mon please,” he pleaded, grabbing onto the controls, “We need to go now!”

He closed his eyes and focused on their connection. There was still interference, but he could feel her presence around him. When he opened his eyes, the displays were still dark but he could see through _her_ eyes.

“Let’s go!” he yelled, and together they pulled away from the vines and into the air.

They set their sights on the ceiling, and Keith scanned for an opening. He braved a look down and felt his stomach drop as he watched the giant bulb start to glow purple with magic. Of course, he realized, it must be an experiment of the druids. That’s why it could mess with their equipment.

Goosebumps ran up his arms as the dark magic settled onto them. They were so close to the top but the Black Lion was losing altitude again.

With one last effort he picked a spot on the ceiling and fired.

 

Keith prepared for another impact with the ground, but it never came. He opened his eyes and laughed out loud when he realized that the Yellow and Green Lions were supporting him from either side.

Keith watched as the Red and Blue Lions came through the hole he’d made in the ceiling and fire at the central bulb, causing the purple glow to subside.

“We got you buddy!” Hunk yelled through the comms.

A flash and a pathetic whine beside him let him know that his space wolf had boarded, and he reached out a hand to scratch behind his ears. A hand on his shoulder let him know that the wolf hadn’t come alone.

“Missed me?” Keith asked, glancing back at Shiro with a smile.

Shiro’s hand squeezed his shoulder a bit tighter, and instead of answering outright, he leaned down to press a kiss to Keith’s lips.

“I found you,” Shiro finally replied.

“Okay you guys, stop being so sappy,” Lance’s voice came through, and Shiro shot back upright, “Don’t we have a big creepy flower to kill?”

“Alright,” Keith replied, refocusing on the battle at hand, “This thing has done enough damage to the planet! We need to end this! Form Voltron!”

“Yeah!” Everyone yelled in unison.

Beside him, Shiro still held onto his shoulder, and he felt Shiro pour his own strength and will into the Black Lion with him.

“Form flaming sword!” Keith yelled and together the six of them thrust the sword straight through the giant bulb.

 

Shiro balanced the tray of food on his prosthetic while he keyed in the code to their room with his other hand. As the door slid open, his eyes immediately landed on Keith who was changing out of his paladin armor.

Shiro entered, setting the tray down in order to go behind Keith to help him unzip his black undersuit.

“Thanks,” Keith smiled, shucking the rest of the armor until he was in nothing but his boxers, “Is that food from Hunk? I’m starving.”

Shiro laughed, watching Keith pad over to the tray.

He felt warmth bubble in his chest and he felt as though he could finally relax now that Keith was safely back onboard the Atlas. He leaned back onto the bed and watched Keith wolf down his food.

After the killer plant’s destruction the Dregmos had honored Voltron with many gifts and thanks. Shiro had handled the rest of the diplomatic meetings regarding their alliance with the Voltron coalition while Allura had used whatever power she could to start the healing process of the planet. Hours later, Shiro was acutely aware of just how long he’d been awake.

He yawned and let his eyes drift closed and it seemed like only moments later that Keith sank onto the bed beside him, coming up to rest his head on Shiro’s chest. Shiro’s flesh hand settled on Keith’s head, finding his hair wet from the shower he must have just took.

“Sorry,” he yawned again, “I must have fallen asleep.”

“Did you not sleep while I was gone?” Keith asked, lifting his head to meet Shiro’s eyes.

Shiro shook his head and Keith huffed out a sigh.

“Sleep,” he said, pecking Shiro on the lips before resting his head back down on Shiro’s chest, “I promise I’ll be here when you wake up.”

Shiro smiled, his arms encircling Keith’s waist, “I know.”

**Author's Note:**

> Merry Christmas! Thank you for reading and I hope this was something you liked bakuraes!


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